JP2871270B2 - Slope estimation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope estimating method for estimating a slope condition used as a parameter for executing various traveling controls of an automobile or the like, that is, a condition such as uphill, downhill and its gradient. is there.

[0002]

2. Description of the Related Art Conventionally, as this kind of technique, for example, Japanese Unexamined Patent Publication No. 1-112063 discloses a technique of estimating a slope used for executing a shift control of an automatic transmission. According to the technique disclosed in this publication, a predicted acceleration on a flat road with no gradient, which uses the accelerator pedal depression amount (accelerator depression amount) and the vehicle speed (vehicle speed) as parameters, is determined in advance for each gear position and mapped. Has been remembered.
Then, by comparing the actual acceleration obtained by differentiating the vehicle speed obtained when the vehicle is traveling with the predicted acceleration obtained from the map, the uphill, downhill and the degree of the gradient are estimated. Had become.

[0003]

However, in the prior art, since the predicted acceleration on a flat road is obtained from the accelerator pedal depression amount and the vehicle speed, there is a problem in determining the predicted acceleration. That is, even when the accelerator pedal depression amount becomes constant, the fact that the pedal depression amount is reflected in the actual acceleration is after a lapse of a predetermined time after the pedal depression amount becomes constant.
Therefore, when the accelerator pedal depression amount changes greatly in a short time, the predicted acceleration cannot be accurately obtained unless the predicted acceleration is determined so as to follow the change in the accelerator pedal depression amount. Therefore, the gradient could not be accurately estimated with the predicted acceleration.

The present invention has been made in view of the above-mentioned circumstances, and has been made in consideration of the fact that the fuel efficiency of an internal combustion engine reflects a change in conditions of a slope gradient well. It is an object of the present invention to provide a slope estimating method capable of estimating a slope gradient during traveling with high accuracy.

[0005]

In order to achieve the above object, according to the present invention, the amount of fuel actually supplied to an internal combustion engine within a predetermined period of time while a motor vehicle powered by the internal combustion engine is running is determined. The actual fuel efficiency of the internal combustion engine is calculated based on the actual travel distance of the vehicle within the time, and the actual travel speed of the vehicle is determined based on the fuel efficiency data determined in advance by using the travel speed as a parameter. Of the reference fuel efficiency, and further, the corrected reference fuel efficiency is determined by correcting the determined reference fuel efficiency with various operating parameters that can affect the actual fuel efficiency. The degree of the current slope gradient is estimated from the difference from the corrected reference fuel efficiency.

[0006]

According to the above arrangement, the actual fuel efficiency, which can be well reflected by the change in the condition of the slope, is compared with the corrected reference fuel efficiency, and the degree of the slope is estimated from the difference between the two fuel efficiencies. . In addition, the reference fuel efficiency, which is the basis of the corrected reference fuel efficiency, is determined from fuel efficiency data that is determined in advance by using the traveling speed with less rapid change as a parameter. Therefore,
The difference between the actual fuel efficiency and the corrected reference fuel efficiency is determined as having relatively little change, and the degree of the slope gradient estimated from the difference is also stable with little change.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a slope estimating method according to the present invention;

FIG. 10 is a schematic diagram showing a gasoline engine system serving as a driving source of an automobile in this embodiment. The engine 1 as an internal combustion engine includes an intake passage 2 forming an intake system, and an exhaust passage 3 forming an exhaust system. An air cleaner 4 is provided on the inlet side of the intake passage 2. The downstream side of the intake passage 2 is connected to each cylinder (in this case, 4 cylinders) of the engine 1 through a branched intake manifold 2a.
Cylinder). In the vicinity of the intake manifold 2a, injectors 5A, 5B, 5C, 5D for fuel injection are provided.
Are provided for each cylinder. As is well known, fuel at a predetermined pressure is supplied to each of the injectors 5A to 5D from a fuel tank (not shown) by operating a fuel pump. Each cylinder of the engine 1 is provided with a spark plug 6A, 6B, 6C, 6D. On the other hand, the exhaust passage 3 communicates with each cylinder of the engine 1 through a branched exhaust manifold 3a. Further, a catalyst converter 7 having a built-in three-way catalyst is provided on the outlet side of the exhaust passage 3.

Then, outside air is taken into the engine 1 from an air cleaner 4 through an intake passage 2. At the same time as the intake of the outside air, fuel is injected from each of the injectors 5A to 5D into the vicinity of the intake manifold 2a, so that a mixture of the fuel and the outside air is taken into each cylinder of the engine 1. Then, the taken-in air-fuel mixture explodes and burns in the combustion chambers of the respective cylinders by the operation of the ignition plugs 6A to 6D, so that a piston and a crankshaft (not shown) are operated to reduce the driving force of the engine 1. can get. The burned gas that has been burned in the combustion chamber of the engine 1 is guided to the exhaust passage 3 as exhaust gas, purified by the catalytic converter 7, and then discharged to the outside.

In the middle of the intake passage 2, a linkless type throttle valve 8 is provided. That is, the throttle valve 8 is opened and closed by the operation of a DC motor 9 provided in the vicinity thereof, and the support shaft of the throttle valve 8 is connected to the output shaft of the DC motor 9. When the throttle valve 8 is opened and closed, the intake passage 2 is opened.
Then, the intake air amount Q to each cylinder is adjusted.

In the vicinity of the throttle valve 8, there is provided a throttle sensor 21 for detecting the actual opening, that is, the throttle opening TA. An air flow meter 22 for detecting an intake air amount Q in the intake passage 2 is provided upstream of the intake passage 2. Further, in the middle of the exhaust passage 3, the oxygen concentration Ox in the exhaust gas,
Is provided with an oxygen sensor 23 for detecting the exhaust air-fuel ratio at. Further, the engine 1 is provided with a water temperature sensor 24 for detecting the temperature of the cooling water, that is, the cooling water temperature THW.

An ignition signal distributed by a distributor 10 is applied to ignition plugs 6A to 6D provided for each cylinder of the engine 1. Distributor 10
Is for distributing the high voltage output from the igniter 11 to the ignition plugs 6A to 6D in synchronization with the crank angle of the engine 1. And, each of the ignition plugs 6A to 6D
The ignition timing is determined by the high voltage output timing from the igniter 11.

The distributor 10 is provided with a rotation speed sensor 25 for detecting the rotation speed (engine rotation speed) NE of the engine 1 from the rotation of a rotor (not shown). Further, each of the distributors 10 is provided with a cylinder discrimination sensor 26 for detecting a change in the crank angle of the engine 1 at a predetermined rate in accordance with the rotation of the rotor. In this embodiment, assuming that the crankshaft makes two revolutions for a series of four strokes (intake stroke, compression stroke, expansion stroke, and exhaust stroke) of the piston in the engine 1, the cylinder discrimination sensor 26 detects the ratio of 360 ° CA. Is used to detect the crank angle.

In this embodiment, the driver's seat is provided with an accelerator pedal 12 which is depressed by the driver. In the vicinity of the accelerator pedal 12, an accelerator sensor 27 for detecting the operation amount, that is, the accelerator opening ACCP is provided.

Further, in this embodiment, the engine 1 is provided with a starter 13 for applying a rotational force by cranking at the time of starting. Further, the starter 13 is provided with a starter switch 28 for detecting the on / off operation. As is well known, the starter 13 is turned on and off by operating an ignition switch (not shown). While the ignition switch is being operated, the starter 13 is turned on and the starter switch 28 is turned on by the starter switch 28. The signal STS is output.

In addition, an electronic control transmission (ECT) 14 is drivingly connected to the engine 1 of this embodiment, and driving wheels (not shown) are drivingly connected to an output shaft of the ECT 14. The ECT 14 includes a torque converter 14A that is drivingly connected to the engine 1, and a planetary gear-type gear transmission mechanism 14B that is drivingly connected to driving wheels.
The torque converter 14A has a built-in lock-up clutch mechanism, and the gear transmission mechanism 14B has four forward speeds and one reverse speed. Furthermore, ECT14
Is provided with an actuator 15 which is drive-controlled to switch the lock-up clutch mechanism and each shift speed and includes a plurality of solenoids.

The ECT 14 has a gear transmission mechanism 14B.
A shift sensor 29 which detects the shift position (first speed, second speed, third speed, fourth speed, reverse) and outputs the same as a shift position signal SPS. Further, the ECT 14 is provided with a vehicle speed sensor 30 which detects the rotation of the gear transmission mechanism 14B and outputs it as a running speed (vehicle speed) SPD of the vehicle.

The aforementioned throttle sensor 21, air flow meter 22, oxygen sensor 23, water temperature sensor 24, rotation speed sensor 25, cylinder discrimination sensor 26, accelerator sensor 2
7, signals from the starter switch 28, the shift sensor 29, the vehicle speed sensor 30, etc.
1 is input. The engine computer 41 includes an input / output interface for inputting / outputting various signals, a central processing unit (CPU) for executing predetermined calculations / controls based on the input signals, and various types for storing calculation results and the like in the CPU. It is configured by a microcomputer having a memory and the like. Then, the engine computer 41 includes various sensors 21, 23 to 27, 2
9, 30 and read various signals from the air flow meter 22, the starter switch 28, and the like, and appropriately drive control the injectors 5A to 5D in order to perform fuel injection control according to the operating state based on those signals. ing. Further, the engine computer 41 suitably controls the drive of the igniter 11 in order to execute the ignition timing control according to the operating state based on the various signals read in the same manner. Further, the engine computer 41
The drive of the DC motor 9 is suitably controlled in order to execute the opening / closing control of the throttle valve 8 according to the operating state based on the various signals read in the same manner.

As described above, the engine computer 41
Is a device that controls fuel injection control, ignition timing control, and throttle valve control. In addition, in this embodiment, ECT
An ECT computer 42 for controlling the lock-up control and the shift control in 14 is provided. This EC
The T computer 42, like the engine computer 41, is configured by a microcomputer including an input / output interface, a CPU, various memories, and the like.
The ECT computer 42 reads the shift position signal SPS from the shift sensor 29. Further, in this embodiment, the ECT 14 can be switched between three operation modes of “power”, “normal” and “economy”. Is provided with a mode switch 31 operated by the driver. The mode switch 31 outputs a mode signal MS for specifying each operation mode set by the operation. E
The CT computer reads the mode signal MS. Further, the ECT computer 42 exchanges data with the engine computer 41, and the various sensors 2
Various signals from 1, 23 to 27, 29, 30, the air flow meter 22, the starter switch 28, and the like are read, respectively. Then, the ECT computer 42 outputs a shift / lock-up signal SLS to the actuator 15 according to the current shift condition based on the various signals.
The drive of the CT 14 is suitably controlled.

In addition, in this embodiment, a slope estimating computer 43 for estimating a slope while the vehicle is running is provided. The slope estimation computer 43, like the engine computer 41, is configured by a microcomputer including an input / output interface, a CPU, various memories, and the like. The slope estimation computer 43 reads the mode signal MS from the mode switch 31 and monitors and reads the shift / lockup signal SLS output from the ECT computer 42 to the actuator 15. The slope estimation computer 43 calculates
From the engine computer 41, each injector 5A-5
Monitor and read the injector energizing signal (+ B) output to D. Further, in this embodiment, an air conditioner switch 32 that detects the operating state (on / off) of an air conditioner (not shown) and outputs the air conditioner signal ACS.
Is provided, and the slope estimation computer 43 reads the air conditioner signal ACS. The slope estimation computer 43 exchanges data with the engine computer 41, and reads various signals such as the engine speed NE, the vehicle speed SPD, and the starter signal STS from the engine computer 41. And the slope estimation computer 4
Numeral 3 executes a slope estimation process based on the read various signals, and outputs the process result to the engine computer 41.

Next, in the gasoline engine system configured as described above, the processing operation of the slope estimation performed by the slope estimation computer 43 will be described. FIG. 1 is a flowchart for explaining the “slope estimation processing routine”. The processing is started by inputting a starter signal STS of “ON”.

When the process is started, first, at step 100
In, initialization is performed. In this initialization, various calculation results obtained in the operation up to the stop are reset. Subsequently, in step 200,
The actual fuel efficiency of the engine 1 at that time, that is, the actual fuel efficiency R2 is calculated. In step 300, the reference fuel consumption R10 at that time is calculated. Step 400
, The corrected reference fuel consumption R1 is calculated from the reference fuel consumption R10. Then, in step 500, the slope gradient R
Calculate θ. Then, from step 200 to step 5
The process of 00 is periodically repeated.

Here, the processing in step 200 will be described in detail with reference to the flowchart of the "actual fuel consumption calculation routine" shown in FIG. That is, first, in step 210, the injector energization signal (+ B) output to each of the injectors 5A to 5D is monitored to measure the injector energization time tTAUINJ. Further, based on the injector energizing signal (+ B), the invalid injection time TAUV is calculated with reference to a map as shown in FIG. In this map, for the injectors 5A to 5D in the present embodiment, the invalid injection time TAUV having the injector energization time (+ B) as a parameter is experimentally determined in advance.

In step 220, the invalid injection time TAUV is calculated from the injector energization time tTAUINJ.
Is set as the effective injection time TAUE. Subsequently, in step 230, “100 ms”
Effective injection time TAUE per injector from injector 5A ~
The injection amount TAU matching the 5D characteristic is calculated.

Further, at step 240, the vehicle speed SPD from the engine computer 41 is read. Then, at step 250, the currently read vehicle speed S
Based on the PD, the travel distance L per “100 ms” is calculated.

Next, at step 260, based on the injection amount TAU and the traveling distance L obtained this time, "10
The fuel efficiency R20 per “0 ms” is calculated. In step 270, the average fuel consumption R20AVE is calculated from the data of the total 100 fuel consumptions R20 obtained before and including the fuel consumption R20 obtained this time. That is, here, the average fuel consumption R20AVE for “10 seconds” is obtained.

Then, in step 280, the average fuel consumption R20AVE obtained this time is set as the actual fuel consumption R2, and this processing routine ends. That is, in the “actual fuel consumption calculation routine”, the engine injection amount is calculated based on the injection amount TAU of the fuel actually supplied to the engine 1 in “10 seconds” and the travel distance L of the vehicle actually traveled in “10 seconds”. The actual fuel consumption R2 at 1 is obtained. Here, it has been experimentally confirmed that the required actual fuel efficiency R2 well reflects a change in the condition of the slope.

Next, the processing in step 300 will be described with reference to FIG.
Will be described with reference to the flowchart of the “reference fuel efficiency calculation routine” shown in FIG. In this routine, first, step 310
The vehicle speed SPD from the engine computer 41
Read. Then, in step 320, the reference fuel consumption R10 is calculated from the vehicle speed SPD with reference to a map as shown in FIG. 5, and the processing routine is terminated. In this map, the vehicle speed S for the engine 1 of this embodiment is
A reference fuel consumption R10 using PD as a parameter is experimentally determined in advance.

That is, in the "base cost calculation routine", the base fuel consumption R10 relative to the actual vehicle speed SPD of the vehicle is calculated.
Is required. Next, the processing in step 400 will be described in detail with reference to the flowchart of the "corrected reference fuel consumption calculation routine" shown in FIG.

In this routine, first, at step 410, the engine speed NE from the engine computer 41 is read. Further, based on signals from the shift sensor 29, the mode switch 31 and the air conditioner switch 32, the shift position signal SPS, the mode signal MS and the air conditioner signal ACS are respectively read. Further, the shift / lockup signal SLS is read from the ECT computer 42, and the reference fuel consumption R10 obtained this time is read.

Subsequently, in step 420, it is determined whether or not the air conditioner signal ACS is "OFF". Here, when the air conditioner signal ACS is “OFF”, it is determined that the air conditioner is not operating, and the process directly proceeds to step 430. On the other hand, if the air conditioner signal ACS is not “off”, it is assumed that the air conditioner is operating and the fuel efficiency is deteriorated by 10%, and in step 421, the reference fuel efficiency R10 is set to “0.90”.
Is set as a new reference fuel consumption R10, and the routine proceeds to step 430.

In step 430, the operation mode of the ECT 14 is determined based on the mode signal MS. Here, when the operation mode is “normal”, it is determined that there is no deterioration in fuel efficiency, and the process directly proceeds to step 440. When the operation mode is "economy", assuming that the fuel efficiency is improved by 5%, in step 431, the result of multiplying the reference fuel efficiency R10 by "1.05" is used as the new reference fuel efficiency R10. After setting as
Move to step 440. On the other hand, when the operation mode is “power”, assuming that the fuel efficiency is degraded by 5%, in step 432, the result of multiplying the reference fuel efficiency R10 by “0.95” is used as the new reference fuel efficiency R10. Then, the process proceeds to step 440.

In step 440, the currently read engine speed NE and shift position signal S are read.
From PS, the fuel economy deterioration rate NeH corresponding to the shift speed is calculated. The fuel efficiency deterioration rate NeH is obtained with reference to a map as shown in FIG.

Subsequently, in step 450, the result of multiplying the reference fuel consumption R10 by the fuel consumption deterioration rate NeH is set as a new reference fuel consumption R10. Further, in step 460, based on the shift / lockup signal SLS, E
It is determined whether or not the operation of the CT 14 is lock-up. Here, if the ECT 14 is locked up, it is determined that there is no deterioration in fuel efficiency, and the process directly proceeds to step 470. On the other hand, if the ECT 14 is not locked up, assuming that the fuel consumption is degraded by 5%, the result of multiplying the reference fuel consumption R10 by “0.95” is set as a new reference fuel consumption R10 in step 461. , To step 470.

In step 470, the reference fuel consumption R10 obtained so far is set as the corrected reference fuel consumption R1, and this processing routine ends. In other words, in the "corrected reference cost calculation routine", various operating parameters that can influence the previously calculated reference fuel consumption R10 on the actual fuel consumption R2, that is, the operation of the air conditioner.
The corrected reference fuel consumption R1 is obtained by being corrected by the non-operation, the operation mode of the ECT 14, and the lock-up of the ECT 14.

Finally, the processing in step 500 will be described with reference to the flowchart of the "slope gradient calculation routine" shown in FIG. In this routine, first, in step 51,
At 0, the result obtained by subtracting the corrected reference fuel consumption R1 found this time from the actual fuel consumption R2 found this time is set as the fuel consumption difference R0. Next, in step 520, a slope gradient Rθ is calculated from the fuel consumption difference R0 with reference to a map as shown in FIG. In this map, for the engine 1 of the present embodiment, the slope gradient Rθ using the fuel consumption difference R0 as a parameter is experimentally obtained in advance. In this slope gradient Rθ, a plus value corresponds to an uphill slope, and a minus value corresponds to a downhill slope. Then, in step 530, the value of the slope gradient Rθ obtained this time is output to the engine computer 41, and this processing routine ends.

That is, this "slope slope cost calculation routine"
Then, the present slope gradient Rθ is calculated from the fuel consumption difference R0 between the actual fuel consumption R2 determined this time and the corrected reference fuel consumption R1 determined this time.
Is estimated.

In this embodiment, the value of the slope Rθ output to the engine computer 41 is used by the computer 41 as a parameter for fuel injection control and throttle valve control. For example, as fuel injection control, it can be used for fuel increase correction during uphill or fuel cut during downhill. Further, as the throttle valve control, the opening characteristic gradient of the throttle valve 8 can be made steep during uphill and the opening characteristic gradient of the throttle valve 8 can be made gentle during downhill.

As described above, according to the slope estimating method of this embodiment, the actual fuel efficiency R2, which can change and reflect the change in the condition of the slope gradient Rθ, is compared with the corrected reference fuel efficiency R1, and the two are compared. The degree of the slope gradient Rθ is estimated from the fuel consumption difference R0. Moreover, the corrected reference fuel efficiency R
The reference fuel consumption R10 as a basis of 1 is obtained from a map of fuel consumption data determined in advance using the vehicle speed SPD with little rapid change as a parameter. Therefore, the fuel efficiency difference R0 is determined as having relatively little change, and the degree of the slope gradient Rθ estimated by the fuel efficiency difference R0 is also stable with little change.

Therefore, the actual fuel consumption R2 in the case where the throttle opening degree TA changes greatly in a short time due to the driver stepping on or releasing the accelerator pedal 12, or the depression of the accelerator pedal 12 is kept constant. The actual fuel efficiency R2 in the case is also reflected in the fuel efficiency difference R when actually reflected in the vehicle speed SPD.
In all cases, the actual fuel efficiency R2
Is the same. As a result, an accurate slope gradient Rθ can be obtained from the fuel consumption difference R0 regardless of the operation state of the accelerator pedal 12 while the vehicle is running, and the slope gradient Rθ can be estimated with high accuracy. The goodness of the estimation accuracy is apparent, in particular, as compared with the case where the estimation is made by comparing the actual acceleration and the predicted acceleration in the related art.

In this embodiment, the slope gradient Rθ is obtained by the above estimation method, and no special equipment such as a gravity sensor or an inclinometer is used. Become.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows, with a part of the configuration being appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the reference fuel consumption R10 is corrected as various operating parameters that can affect the actual fuel consumption R2 based on the operation / non-operation of the air conditioner, the operation mode of the ECT 14, the presence / absence of lockup, and the like. Although the corrected reference fuel consumption R1 has been obtained, it may be corrected by other operating parameters.

(2) In the above-described embodiment, the estimated slope gradient Rθ is used as a parameter for fuel injection control and slot valve control. Control), control of torque distribution to the drive wheels during uphill and downhill, control of roll rigidity distribution, control of braking force distribution, and the like.

[0044]

As described above in detail, according to the present invention, the actual fuel efficiency that can be changed by reflecting the change in the condition of the slope gradient can be compared with the corrected reference fuel efficiency obtained from the reference fuel efficiency using the traveling speed as a parameter. By comparing the two fuel consumption differences, the degree of the slope gradient is estimated from the difference between the two fuel consumptions, so that the change in the slope gradient estimated from the fuel consumption difference with relatively little change is reduced, and the slope gradient during driving of the vehicle is increased. It has an excellent effect that it can be estimated with high accuracy.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a “slope estimation processing routine” in an embodiment embodying a slope estimation method of the present invention.

FIG. 2 is a flowchart illustrating a “real fuel consumption calculation routine” in a “slope estimation processing routine” in one embodiment;

FIG. 3 shows an embodiment of an injector energization signal (+
6 is a map in which the relationship of the invalid injection time to B) is determined in advance.

FIG. 4 is a flowchart illustrating a “reference fuel consumption calculation routine” in a “slope estimation processing routine” in one embodiment;

FIG. 5 is a map in which a relationship between a vehicle speed and a reference fuel consumption is determined in one embodiment.

FIG. 6 is a flowchart illustrating a “corrected reference fuel consumption calculation routine” in a “slope estimation processing routine” in one embodiment.

FIG. 7 is a map in which the relationship between the engine speed and the shift position signal in terms of the fuel consumption deterioration rate is determined in one embodiment.

FIG. 8 is a flowchart illustrating a “slope gradient calculation routine” in the “slope estimation processing routine” in one embodiment.

FIG. 9 is a map in which a relationship between a fuel consumption difference and a slope of a slope is determined in one embodiment.

FIG. 10 is a schematic configuration diagram showing a gasoline engine system to which a slope estimation method is applied in one embodiment.

[Explanation of symbols]

1: engine as internal combustion engine, R2: actual fuel efficiency, R10
... Reference fuel consumption, R1 ... Corrected reference fuel consumption, R0 ... Fuel consumption difference, R
θ: slope gradient, SPD: vehicle speed.

Claims (1)

(57) [Claims] 1. A method for estimating a slope which is performed during the running of an automobile using an internal combustion engine as a power source, comprising: a fuel amount actually supplied to the internal combustion engine within a predetermined time; The actual fuel efficiency of the internal combustion engine is obtained based on the travel distance, and the reference fuel efficiency for the actual running speed of the vehicle is subsequently determined based on the fuel efficiency data obtained by previously determining the reference fuel efficiency of the internal combustion engine using the running speed as a parameter. Further, the corrected reference fuel efficiency is determined by correcting the determined reference fuel efficiency with various operating parameters that can affect the actual fuel efficiency.Finally, the actual fuel efficiency determined this time and the actual fuel efficiency determined this time are determined. A slope estimating method characterized by estimating a degree of a current slope gradient from a difference from the corrected reference fuel efficiency.